OP0280-HPR VALIDATION OF A NEW GLUCOCORTICOID-SPECIFIC PATIENT REPORTED OUTCOME QUESTIONNAIRE (THE STEROID PRO)
Authors: S. Bridgewater, M. Ndosi, J. Dawson, P. Richards, C. Silverthorne, E. Dures, S. Goodman, C. Hill, S. Mackie, J. Robson
Journal: Annals of the Rheumatic Diseases (2023)

<h3>Background</h3> Glucocorticoids are used in the treatment of a broad range of rheumatic conditions but can have a significant impact on health-related quality of life[1]. In-depth qualitative interviews with patients who have experience of glucocorticoid treatment for their rheumatic disease, from the UK, USA and Australia, were used to develop candidate items for a treatment-specific Patient Reported Outcome Measure (PROM): the Steroid PRO. <h3>Objectives</h3> We aimed to complete the development and validation of the Steroid PRO through use of a cross-cultural validation study. <h3>Methods</h3> This was a cross-sectional online study of adults taking glucocorticoids for a rheumatic disease, from the UK, USA, Australia and New Zealand. A steering committee comprising methodologists, clinicians and patient research partners (PRPs) oversaw the study. The survey was distributed via social media with support from patient groups. Baseline data included: (i) demographics - age, gender, country, ethnicity, educational level; (ii) clinical information - diagnosis, glucocorticoid dose; (iii) 40 candidate items for the Steroid-PRO, developed in a previous qualitative study; (iv) EQ5D-5L. Optional follow-up data collected 3-5 days later: (i) the Steroid PRO candidate items; (ii) a condition change question. After descriptive analysis, iterative testing with Rasch measurement model and exploratory factor analysis (EFA) informed item reduction and established structural validity, reliability and unidimensionality of the final Steroid PRO. Item reduction was based on clinical importance, lack of fit to the Rasch model, and redundancy. Evidence of discriminative validity of the Steroid PRO was established by comparing its scores for participants receiving lower dose glucocorticoid (up to 10 mg) versus higher dose (&gt;10 mg). Intraclass correlation (ICC) between baseline and follow-up was calculated for patients who reported 'no change' compared with 3-5 days ago. <h3>Results</h3> A total of 946 patients returned complete responses at baseline (follow-up: 447 responses). They were from UK, n=743 (78.5%); USA, n=139 (14.7%); Australia, n=59 (6.2%). Their mean age was 57.6 (SD=13.6); 833 (88%) were women. They were treated for inflammatory arthritis (n=194), connective tissue disease and/or vasculitis (n=398), and giant cell arteritis and/or polymyalgia rheumatica (n=341). A total of 25 items were removed due to floor effects and lack of fit to the Rasch model. Iterative discussions between statisticians, clinicians and PRPs ensured that items of high clinical importance were retained. The remaining 15 items showed a satisfactory fit to the model. EFA suggested a scale structure with four domains: Participation (4 items), Appearance (3 items), Psychological (5 items), and Treatment concerns (3 items). PRPs were involved in naming the domains. The 4-domain structure was supported by the Rasch model, confirming construct validity; χ2=47.82 (DF=36), p=0.899; and reliability (Person Separation Index, PSI=0.757). Total scores also fitted the Rasch model, therefore both domain and total scores will be psychometrically appropriate for use as a repeated measure. A good fit to the Rasch model was also seen across the disease groups with items distributed equally across the three groups. Patients on a lower glucocorticoid dose had lower Steroid PRO domain scores than those receiving higher dose (discriminant validity). ICC between baseline and follow-up ranged from 0.892 to 0.942 (95%CI 0.868 to 0.953) suggesting excellent (test-retest) reliability. <h3>Conclusion</h3> The final Steroid PRO is a 15-item, valid and reliable 4-domain scale measuring the impact of glucocorticoid therapy on HRQoL of people with rheumatic diseases. <h3>Reference</h3> [1]Cheah, J. T. L.; Robson, J. C.; Black, R. J.; Goodman, S. M.; Lester, S.; Mackie, S. L.; Hill, C. L., The patient's perspective of the adverse effects of glucocorticoid use: A systematic review of quantitative and qualitative studies. From an OMERACT working group. Seminars in arthritis and rheumatism 2020 50 (5), 996-1005. <h3>Acknowledgements:</h3> NIL. <h3>Disclosure of Interests</h3> Susan Bridgewater Grant/research support from: Vifor Pharma, Mwidimi Ndosi Grant/research support from: Vifor Pharma, Jill Dawson: None declared, Pamela Richards: None declared, Christine Silverthorne: None declared, Emma Dures Grant/research support from: Vifor Pharma, Susan Goodman Consultant of: UCB, Grant/research support from: Novartis, Catherine Hill: None declared, Sarah Mackie Speakers bureau: Roche/Chugai, Vifor Pharma and Pfizer on behalf of her institution (no personal remuneration), Consultant of: Roche/Chugai, Sanofi, AbbVie, AstraZeneca and investigator on clinical trials for Sanofi and GSK on behalf of her institution (no personal remuneration), Grant/research support from: Vifor Pharma as research grant co-applicant (partial salary support) paid to her institution, Joanna Robson Speakers bureau: Vifor Pharma, Consultant of: Vifor Pharma, Grant/research support from: Vifor Pharma.